1. Field of the Invention
The present invention relates to a coplanarity detecting apparatus, an electronic-component-condition detecting apparatus, and an electric-component mounting system, and particularly to the art of quickly carrying out detection or mounting.
2. Discussion of Related Art
There is known an electronic component including a main portion or body and a plurality of leads laterally extending from the main body, and there are some cases where it is needed to detect a coplanarity of the leads, that is, a degree of positioning of respective end portions of the leads in a same plane. For example, in the case where the electronic component is mounted on a printed-wiring board, the leads are placed on, and connected to, an electric circuit provided on the printed-wiring board. However, if the component has one or more upwardly deformed leads, those leads cannot contact the circuit, which leads to producing a defective circuit.
Conventionally, a laser length measuring machine has been used to detect coplanarity, i.e., measure a height position of each of the leads. If the leads includes a deformed lead, an end portion of the deformed lead has a height position different from those of respective end portions of the other leads, and is deviated from a plane in which the end portion of the lead should be positioned. Thus, the coplanarity of the leads can be detected. To this end, the electronic component is moved relative to the laser length measuring machine, while the respective height positions of respective end portions of the leads are sequentially measured by the measuring machine.
However, the laser length measuring machine has various problems. For example, if an electronic component is rotated out of position about an axis line perpendicular to an upper surface thereof and accordingly has an angular-positional error relative to the measuring machine, in a plane parallel to the upper and bottom surfaces thereof, one or more leads may not be aligned with the measuring machine, when the component is moved relative to the machine, and accordingly respective height positions of those leads may not be measured. In this case, a coplanarity of the leads may not be detected.
If a preliminary inspection is carried out, before a coplanarity detection is done, to take an image of an electric component as viewed in a direction perpendicular to a bottom surface of the component, a possible angular-positional error of the component can be corrected based on the thus taken image. In this case, respective height positions of all the leads can be measured, and a coplanarity of the leads can be detected. However, since the preliminary inspection is needed, a time needed to carry out the coplanarity detection is increased as such.
In a particular case where it is needed to detect a positional error of an electric component held by a holding device, relative to the holding device, in a direction parallel to an upper surface of the component, a time needed to carry out a coplanarity detection is not increased if an image of the component taken for detecting the positional error is also used for carrying out a preliminary inspection. However, if the component is rotated to detect coplanarity and then is rotated back to an initial position at the time of preliminary inspection, i.e., positional-error detection, the component cannot be accurately back to the initial position because of inevitable rotational error thereof. Thus, the positional error detected previously may not be equal to an actual positional error of the component. To solve this problem, it is needed to take another image of the component, thereby increasing the time needed to carry out the coplanarity detection.
In addition, the laser length measuring machine is expensive, which leads to increasing the cost of coplanarity detection.